Cardinal

Cardinal is a free, open‑source virtual modular synthesizer that runs as a plugin (AudioUnit, CLAP, LV2, VST2, VST3) and as a standalone application on Linux, macOS, Windows, FreeBSD and the Web. It embeds the VCV Rack engine together with a selection of third‑party and internal modules, providing a self‑contained binary that does not rely on external module libraries or the official Rack store. The plugin replaces Rack’s core modules with Cardinal equivalents that are simplified for plugin use, and all VCV branding has been removed.

The software offers several plugin variants to suit different host requirements: a “main” version with eight audio I/O ports and ten CV ports, a “Synth” version that functions as an instrument with two audio outputs, and an “FX” version that acts as an effect with two audio inputs and outputs. A minimal “Mini” variant is also available as LV2 and standalone, featuring a small hand‑picked module set and limited I/O for DSP/UI separation.

Cardinal is considered stable, with official builds for multiple architectures and both 32‑bit and 64‑bit Windows, as well as universal macOS binaries. Users can obtain releases from the project’s GitHub page, follow the wiki for installation, or compile from source using the provided build instructions. Experimental support for CLAP and VST3 hosting is present, and nightly builds are